The class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon are known in the art. An early disclosure of the production of such materials was by Nozaki, U.S. Pat. No. 3,694,412, who employed monodentate aromatic phosphine complexes of palladium moieties and certain inert solvents. More recent processes for the production of such polymers are disclosed by a number of published European Patent Applications including 121,965, 181,014, 213,671 and 257,663. These polymers, now known as polyketones or polyketone polymers, are represented by the repeating formula EQU --CO--A--
wherein A represents a moiety of at least one ethylenically unsaturated hydrocarbon polymerized through the ethylenic unsaturation thereof. The scope of the polymerization process illustrated by the above European Patent Applications is extensive but, without wishing to be limited, a preferred catalyst composition is formed from a compound of palladium, an anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorus. These catalysts are typically homogeneous catalysts, i.e., the catalysts are soluble in the reaction media, and are used in quantities which are relatively small relative to the reactants.
Recovery of the catalyst from the reaction media is desirable for a number of reasons including the economic advantages obtained by being able to reuse the catalyst components and also from a product purity standpoint.
One method proposed for providing greater possibilities for catalyst recovery is by employing a catalyst composition formed in part from a modified phosphorus ligand. In copending U.S. patent application Ser. No. 479,923, filed Feb. 14, 1990, a bidentate phosphorus ligand also containing a hydroxyl group is reacted with a modifier compound, typically an inorganic solid, to produce an immobilized bidentate phosphorus ligand. The nature of the hydroxyl-substituted bidentate ligand is of some importance in how well interaction between the ligand and the modifier compound takes place. The known ligand 1,3-bis(diphenylphosphino)-2-hydroxypropane is useful for the production of immobilized ligands but the hydroxyl group is secondary and somewhat sterically shielded by the diphenylphosphine groups. In Angew. Chem., 100(5), pp. 730-731, the compounds 1,3-bis(diphenylphosphino)-2-hexanol and 1,2-bis(diphenylphosphino)-3-hexanol are disclosed and in J. Coord. Chem., 9(4), pp. 235-244, the compound 1,5-bis(diphenylphosphino)-3-pentanol is disclosed. These bisphosphines have a relatively low activity towards the modifier compound due to steric hindrance and/or the hydroxyl group being secondary rather than primary. It would be of advantage to provide a more active hydroxyl-substituted bidentate phosphorus ligand which will react more efficiently to produce an immobilized bidentate phosphine ligand.